1. Field of the Invention
This invention relates, generally, to electric power systems. More specifically, it relates to mechanical switches (e.g., transfer or disconnect switches) in a hybrid circuit breaker.
2. Brief Description of the Prior Art
A transfer switch is an electrical component capable of transferring loads between multiple sources. In the past, fast transfer switches have been developed from Thomson coils, power electronics, propellant-based systems, or coupled electromechanical and hydraulic systems. However, each of the foregoing is flawed. Thomson coils require high current pulses, power electronics switches have significant conduction losses, propellant based systems cannot be automatically reset, and coupled electromechanical and hydraulic systems can be complex and slow.
For conventional disconnect switch applications where non-current-carrying electrical conductors are physically moved to achieve separation from each other, and thus creating electrical isolation, coupled mechanical systems are used to separate the contacts enough so that the voltage withstand of the contact gap is sufficient for the application. This contact separation is conventionally achieved by an indirect application of force through a series of levers, a direct application of force with the contacts enclosed in a vacuum or pressurized gas medium (called the switching chamber), or a combination of the two methods. One of the drawbacks of these methods is the fact that they are too slow and cumbersome in achieving the necessary voltage withstand capability for ultrafast medium voltage (1 kV-69 kV) switching applications. Such types of disconnect switches are not suitable for the hybrid power electronics and mechanical disconnect switch that are currently being developed around the world.
To handle high magnitude fault currents in a system, large, slow circuit breakers are typically used. However, the need to deal with these fault currents can be replaced with a need to operate as fast as possible to provide sufficient flexibility and re-configurability of the system.
Accordingly, what is needed is an ultrafast disconnect/transfer switch that is simple, compact, does not need high energy to operate (relative to the Thomson coil designs), ultralow loss (relative to the power electronic solution), clean, and capable of being automatically reset (as compared to the propellant based systems), thus providing more effective control over use and control of power. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how the shortcomings of the prior art could be overcome.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention. Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.